Question
Answers

Why is phosphorus stored in the water?
(A) It is very reactive
(B) It does not react with water
(C) It reacts with air and catches fire
(D) All of the above

Answer Verified Verified
Hint: We should know that phosphorus is an element of the nitrogen family. The reason for the storage of a substance in a particular material is to preserve the substance in its actual form otherwise its contact with some environmental factors can lead to its deformation.

Complete step by step answer:
Phosphorus has the symbol P and atomic number 15.
Phosphorus is found in three forms: white, red, and black.
White phosphorus is a soft, waxy, flammable substance, consisting of tetrahedral $P_4$ molecules; it is often slightly yellowish because of the presence of impurities. It is highly reactive and spontaneously ignites at about 30°C in moist air. It is usually stored underwater, to prevent exposure to the air.
Red phosphorus is stable at room temperature but can be converted to the more reactive form white phosphorus by heat.
Black phosphorus is least reactive, and has little commercial value, but can be converted to white phosphorus by heating it under pressure.
 The allotropic form of white phosphorus is less stable and therefore highly reactive.
$P_{ 4 } +5O_{ 2 } \rightarrow P_{ 4 }O_{ 10 }$
Hence, it is kept in water to avoid Oxidation by the Oxygen present in the Air. Phosphorus is insoluble in water.

Therefore, we can conclude that the correct answer to this question is option D.

Note: We should also know that Sodium reacts vigorously with air which prevents it from being stored outside kerosine.
Sodium does react rapidly with the water vapor and oxygen in the air and therefore must be protected from it in order to remain in elemental form.